[David F.]

I mixed up a test batch of Steven Hill's Strontium Crustal Magic -
Cust Feld 40.0
Whiting 15.2
Stontium Carb 11.1
EPK 13.1
Frit 3124 4.0
Lithium Carb 4.0
titanium Diox 12.1

Yellow iron ox 2.5
Bentonite 2.0

But I don't have all of these so this is the recipe that I mixed
G200 40.4
Whiting 15.2
Strontium Carb 11.1
EPK 13.1
Frit 3124 4.0
Lith Carb 4.0
Titan Diox 12.1

Red iron ox 2.5
Ball Clay 2.0

What do you think the differences will be?

[Marcia Selsor]

I originally said G200 was a soda spar. It is a potash spar. You are fine. It is a pretty good substitution.
The yellow iron, and the ball clay are not as critical, in my opinion.

Marcia

[David F.]

Thanks for responding. I hope the Red iron doesn't make it darker than I want.

[Marcia Selsor]

It is always good to test. I have used Black iron with some interesting results for yellows. Yellow iron is sometimes substituted for yellow umber. You may have to make some alterations and see what happens. Will you have time to test?

Marcia

[TJR]

The bentonite is in there to prevent the glaze from settling in the bucket, and also to help the glaze fit the pot for raw glazing. You could even leave it out. The Red Iron Oxiide is more crucial. It will give you a darker colour than the yellow. You could try dropping it down to 1% in a line blend as a test before you mix your batch.
Tom Roberts.[TJR]

[Marcia Selsor]

If this glaze is normally used on bisqued ware, then adding up to 5% bentonite will help it fit raw clay for single firing.

Marcia

[David F.]

Yes I will test
unfortunately I have added water and can't decrees the percentages.
I believe Steven Hill does single fire many of his pieces, so that may be what the bentonite is for.

[Lynettes]

I have single fired this glaze and used a Australian available potash feldspar that comes from India and it worked fine. I think it needs some oxides to give i ta bit more life. I put less around the bottom third of the pot and it didn't run and added an oribe around the top, over the crystle magic, whcih ran down a small amount. I looks quite nice.

Lynette